Signal transduction is a feature of nearly all eukaryotic cells. One component in many signalling systems is a class of guanine nucleotide-binding regulatory proteins, the "G proteins". These proteins, which may have evolved from a common ancestor, are adapted in diverse ways, both with respect to receptor coupling, target activation and physiologic roles. Originally the province of biochemists studying hormonal modulation of adenylate cyclase, the field has been broadened by links to the visual transduction system, to mechanisms of growth control, and new second messengers such as the phosphoinositides. Progress has been made in understanding the coupling of G proteins with memebrane receptors, and the mechanism whereby they activate target enzymes. Recently, tools of molecular biology and genetics in lower organisms have been applied to the field. Genes encoding components of the system have been cloned, and a relationship has been seen between these proteins and certain cellular oncogenes. The primary objective of the meeting on G Proteins and Signal Transduction is to bring together investigators studying various systems with a variety of approaches to exchange data, techniques and ideas. Hopefully the meeting will accelerate the coherent development of the field by helping to formulate common goals and by establishing new collaborative ties.